Monday, October 4th, 2010 AT 11:45 AM
2002 mazda millenia 2.5L got loud engine noise after start up or idling. The noise seems to almost dissapear or much less noticable. When rpm above 2000rpm. 135K mile. Check engine light on with code 0300, 0350 and 0421. Changed all spark plugs recently. The local mechanics told me the noise seems from inside timing belt cover, front of oil pan, rear upper valve train and water pump. I read one post said bad timing belt tensioner could cause engine noise/knocking. Timing belt never replaced on this car. Can anyone kindly provide the advice or similar experience? Many thanks.

